The red drum Sciaenops ocellatus is a marine fish species of high commercial interest. Despite improvements in current aquaculture practices, there are still concerns about the impact of daily manipulations regarding fish welfare. To investigate how does fish respond to various challenges, S. ocellatus juveniles were submitted to two acute challenges, namely a confinement stress and a cold-temperature shock, as well as a chronic stress challenge consisting of 18 days of repetitive challenge events. The level of cortisol produced by individuals was used as a measure of activation hypothalamic-pituitary-interrenal (HPI) axis. A significant increase in cortisol levels was detected only after the confinement stress. Interestingly, the fish exposed to a chronic stress for 18 days exhibited cortisol levels significantly lower than those of non-challenged fish. The small RNA-sequencing conducted for the chronic stress experiment only allowed us to identify two plasmatic microRNAs more abundant in non-challenged fish (miR-205–1-5p and let-7b-5p) compared to challenged fish. The miR-205–1-5p was of particular interest since it was already detected in previous studies on other fish species. In silico analysis allowed to predict potentially highly conserved mRNA targets of this specific miRNA, among which is tnfrsfa that plays a key role in the secondary stress response.

红石首鱼是一种具有很高商业价值的海洋鱼类。尽管当前水产养殖实践有所改进，但人们仍然担心日常操作对鱼类福利的影响。为了研究鱼类如何应对各种挑战，S. ocellatus幼鱼接受了两种急性挑战，即限制应激和低温冲击，以及由 18 天的重复挑战事件组成的慢性应激挑战。个体产生的皮质醇水平被用来衡量下丘脑-垂体-肾间（HPI）轴的激活程度。仅在限制压力后才检测到皮质醇水平显着增加。有趣的是，受到慢性应激 18 天的鱼表现出的皮质醇水平显着低于未受到应激的鱼。针对慢性应激实验进行的小 RNA 测序仅使我们能够识别出与受到攻击的鱼类相比，未受到攻击的鱼类（miR-205–1-5p 和 let-7b-5p）中含量更丰富的两种血浆 microRNA。 miR-205-1-5p 特别令人感兴趣，因为它已经在之前对其他鱼类的研究中检测到。计算机分析可以预测该特定 miRNA 的潜在高度保守的 mRNA 靶标，其中tnfrsfa在二次应激反应中发挥关键作用。